Amides from alkenes

A similar reaction has been adopted for the preparation of amides from alkenes by the photoaddition of "CONH2 radicals generated from formamide by benzophe-none [7], or via a TBADT [25] photocatalyzed hydrogen abstraction. Solar light has been used in the first case. Furthermore, the introduction of an ester function has been accomplished by generating an alkoxycarbonyl radical by photolysis of [bis(alkoxyoxalyloxy)iodo]benzene at 0-5 °C and ensuing addition to vinyl sulfones in the presence of 1,4-cyclohexadiene [9]. 

Conjugate reductions of unsaturated amides are listed in Section 74D (Alkyls from Alkenes). 

This section contains dehydrogenations to form alkenes and unsaturated ketones, esters and amides. It also includes the conversion of aromatic rings to alkenes. Reduction of aryls to dienes is found in Section 377 (Alkene-Alkene). Hydrogenation of aryls to alkanes and dehydrogenations to form aryls are included in Section 74 (Alkyls from Alkenes). 

As with carboxylic acids obtained by palladium hydroxycarbonylation, their derivatives esters, amides, anhydrides and acyl halides are synthesized from alkenes, CO and HX (X = OR, NR2 etc.). The Pd-catalyzed methoxycarbonylation is one of the most studied reactions among this type of catalyzed carbonylations and has been reviewed and included in reports of homogeneous catalysis.625, 26 The methoxycarbonylation has been applied to many different substrates to obtain intermediates in organic syntheses as well as specific products. For instance, the reaction has been applied for methoxycarbonylation of alkynes666 Highly efficient homogeneous Pd cationic catalysts have been reported and the methoxycarbonylation of alkynes has been used to develop economically attractive and environmentally benign process for the production of methyl... 

By chance, the existence of the borane complex 330 of 329 was discovered. The liberation of 330 occurred with the best efficiency with sodium bis(trimethylsilyl)-amide from the borane complex 327 of 326. When styrene or furan was used as the solvent, three diastereomeric [2 + 2]-cycloadducts 328 and [4 + 2]-cycloadducts 331, respectively, were obtained in 30and 20% yield (Scheme 6.70) [156]. With no lone pair on the nitrogen atom, 330 cannot be polarized towards a zwitterionic structure, which is why its allene subunit, apart from the inductive effect of the nitrogen atom, resembles that of 1,2-cydohexadiene (6) and hence undergoes cycloaddition with activated alkenes. It is noted that the carbacephalosporin derivative 323 (Scheme 6.69) also does not have a lone pair on the nitrogen atom next to the allene system because of the amide resonance. 

The acyclic precursor is an oc, 3-unsaturated amido aldehyde that was condensed with iV-methylhydroxylamine to generate the nitrone ( )-48, which then underwent a spontaneous cycloaddition with the alkene to afford the 5,5-ring system of the isoxazolidinyl lactam 47. The observed product arises via the ( )-nitrone transition state A [or the (Z)-nitrone equivalent] in which the position of the benzyl group ot to the nitrone effectively controls the two adjacent stereocenters while a third stereocenter is predicted from the alkene geometry. Both transition states maintain the benzyl auxiliary in an equatorial position and thus avoid the unfavorable 1,3-diaxial interaction with the nitrone methyl or oxygen found in transition state B. Semiempirical PM3 calculations confirm the extra stability, predicting exclusive formation of the observed product 47. Related cycloadducts from the intramolecular reaction of nitrones containing ester- rather than amide-tethered alkene functionality are also known (83-85). 

In 1948 Ritter5 described a new reaction in which N-substituted amides were prepared from alkenes and nitriles in the presence of a... 

The epoxide can be prepared from an alkene and the amide from a carboxylic acid. The new target. 2-ethyl-2-hexenoic acid, has a CC double bond in conjugation with the carbonyl group of the carboxylic acid. Whenever a compound with an ,/3-unsaturated carbonyl group is encountered, it is worthwhile to consider the possibility of using an aldol condensation (see Section 20.5) or a related reaction to prepare it. To examine this possibility, the aldehyde that will provide the carboxylic acid upon oxidation is disconnected at the double bond. Because both fragments produced by this disconnection are the same, it is apparent that an aldol condensation of butanal can be employed to prepare this compound. The synthesis was accomplished as shown in Figure 23.5. 

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